It appears they didn’t dig up the dirt. They purposely set out to make it up.
I bet you’re right. If you go try to dig up dirt, and can’t find anything, then you just go and make up stories as you go along.
I don’t quite trust Obama and his team. I wouldn’t be surprised if they just go out and make things up, which has the effect of distracting us from the issues, candidates’ records, etc.